Diffusing-container for incandescent lights.



P. G. HEWITT. DIFFUSING CONTAINER FOR INGANDESCENT LIGHTS.

APPLICATION TILED JULY 20, 1911.

Patented Aug. 20, 1912.

Q, ATTORNEY mvrrnn strA'rEs rarnnr Brion.

.PETER COOPER HEWITT, 0F RINGWOOD MANOR, NEW JERSEY.

DIFFUSING-CONTAINER FOR INCANDESCENT LIGHTS.

Original application filed April 8, 1911, Serial No. 519,733. Divided and this application filed July 20,

1911. Serial No. 639,652.

To all whom it may concern:

Be it known that I, PETER CoorER HEW- I'm, a citizen of the United States, and resident of Ringwood Manor, in the county of Passaic and State of New Jersey, have invented certain new and useful Improvements in Diffusing-Containers for Incandescent Lights, of which the following is a specification.

An object of this invention is to produce improved means for diffusing light from a linear source, such, for example, as an incandescent filament or glower.

In the ordinary incandescent lamp, the light emitted from the-incandescent filament passes through the transparent wall of the vacuum container which is usually a blown glass bulb, without being appreciably deflected, 'since the inner and outer surfaces of the container are usually polished and. parallel to each other.

My present invention contemplates shaping the external surface of the vacuum or the other -container surrounding the light ;em1tting filament so that the light emitted from the filament will bedifiused in many directions and from a plurality of points or lines located on the external surface of the container; so that the apparent source of light is the external surface of the container or is diffused from a plurality of points or lines located on the external surface of the container. To this end I fashion all or a considerable portion of the surface of the :container with a multiplicity of minute,

closely spaced, but distinct, well defined elevations and depressions, preferably narrow grooves forming ridges constituting refractors or lens-forming surfaces, the refractors being formed so that rays from the source are separately scattered from amultiplicity of grooves, and blend in the field of illumination to cause the linear source to have the optical appearance of a widened 5? elongated refracting elementsfare employed,

Specification of Letters ratent. Patented AugQZG, 1912.1

so that they cover all or a determined portion of the surface of the container. There is no restriction as to the elongation of the refracting elements and in practice, the series of narrow grooves and ridges, may extend from one end to the other of the lamp bulb and are approximately uniform In the illustrated embodiment of mysin vention, I have provided a series of substantially parallel grooves which are formed on the external face of the vacuum container of an ordinary tungsten incandescent lamp. For the maximum diffusing effect, the. grooves extend approximately parallel to the light emitting. filament of the lamp, the glass wall of the treated portion of the container being in effect thereby formed into a plurality .of linear concave and convex lenses or lens-lure bodies which extend parallel to the longitudinal axis of the vacuum container.

1 One part of myinveirti-o'n which is extremely important both from a commercial and manufacturing standpoint, concerns the application of my invention to thin blown glass vacuum bulbs of incandescent lamps such as are now sold on the market, by minutely fashioning the surface of. the lamp by chemical or abrasive action, preferably by hydrofluoric acid'in desired form or condition or dilution or admixture, and, 'at'the same time, preserving the surface practically smooth. I have discovered that it. :is

possible on commercially thin .bulbs to .pro-

duce an eflicient, and, at the same time, highly ornamental light-diffusing effect by causing light deflection or refraction by means of substantially smooth refractors of high light-transmitting efficiency. This I have been able to accomplish by making grooves narrow enough and close enough so that with a depth not exceeding that which is permissible and safe for such bulbs, the refracting surfaces will nevertheless be steep-sided enough and sharp enough .to

have the desired wide angle light-deflecting effect. The minuteness of width is chiefly controlled by practical optical conditions and the thickness of the wall of the bulb,

and it is obvious that the smaller the de removed and the neater may be the effect.

The etching by the acid may be conducted in such a manner as to leave the surfaces of the depressions and elevations substantially polished or of a vitreous or polished nature. The smooth surfaces of the grooves or ridges may be further polished if desired since the grooves or ridges extend in practically parallel directions. They do not materially lessen the transparency of the glass and do not have the relatively low emissive efficiency of frosted glass surfaces in which there are internal losses due to dirt reflection and refraction, and other losses due to dirt accumulation not be easily removed. I

With my invention, the diffusion of the light is accomplished almost entirely by refraction through the polished surfaces of the linear refracting elements and there is but little, if any, additional obstruction to the passage of light over that ordinarily encountered in a plain, unscreened, transparent container in which the inner and outer surfaces of the walls of the container are parallel to each' other. The light transmitted from a linear filament through a container embodying my invention is subdivided and the image of the filament is so spread out laterally that it ceases to appear to be an incandescent filament but appears more like a wide band of light much less intense per unit of area than the incandescent filament.

In the drawings accompanying, and forming a part of this application, Figure 1 is an elevation of an ordinary tungsten incandescent lamp of commerce, embodying my invention. Fig. 2 is a fragmental sectional view along the line 22 of Fig. 1, and Fig. 3 is a fragmental cross section of a glass container illustrating diagrammatically the convergence and divergence of rays emanating from a single lens-forming. surface or re fracting elementand the convergence of rays emanating from a plurality of such surfaces or elements located on the same container.

In Fig. 1, I have illustrated a well-known form of lamp provided with a linear source of light. The lamp illustrated, as has been said, is an ordinary commercial form of the tungsten incandescent lamp, and is provided with a light emitting filament sus-- pended in zig-zag lengths 1, 1 by arms 2, 2 extending from an axially arranged insulated support 3, carried by standard-4, which contains leading-in wires connecting with the filament. The filament is inclosed within a highly evacuated glass bulb or envelop 5. The filaments of the lamp may be of any known or desired construction and may be composed of carbon, tungsten or tantalum or similar materials which become incandescent when subjected to electric current. In the lamp shown, the filament comwhich can-I prises portions which extend in the same general direction'as the major or longitudinal axis of the bulb and consequently I provide ridges and grooves in the external surface of the bulb 5, which extend lengthwise of the bulb and constitute the refracting surfaces 6, 6.

The shape of the grooves and ridges constituting the refracting elements 6, (i, should be such as to facilitate light emission and substantially prevent losses by internal reflections. In practice the grooves need not be of a very great angle and may be relatively shallow as compared with! their width. The refracting elements. should also be so shaped and located that the filament or object, or both the filament and the object will be out of focus and it is therefore not essential that the refracting elements should be so formed as to have either a point or definite line of focal origin. These grooves, are preferably formed by coating the outer surface of the bulb 5 with a thin skin of wax or asphaltum, or some similar acid resisting material, then scratching through the wax, for the purpose of exposing the surface of the glass along lines of suitable width, and then immersing the bulb in hydrofluoric acid or submitting it to the action of hydrofluoric acid gas. The proper results may be obtained by subjecting the bulb to the action of the acid for about ten minutes. In any ordinary 25 watt tungsten lamp, the lines along which the bulb is etched, may be from 1/100 to 1/250 of an inch from center to center, according to the size and shape of the bulb, the thickness of the Wall and the permissible depth to which it may be etched. l/Vith care, the lines may be spaced closer or farther apart than this, and may be smaller or larger in cross section. The size of the grooves may be determined by practical, rather than theoretical reasons, but the smaller cross section is advisable in practice. In the bulb illustrated, I have so formed the grooves, that the light emitting surface of each refracting element is concave and is curved so that its curved surface represents about 1/3 of the surface of a cylinder.

It will be understood that various methods may be employed in forming the refracting elements on the surface of the bulb, some of which will possibly form truer curved surfaces and more accurately spaced grooves, but in practice, it is not necessary to provide absolutely accurately formed nor accurately spaced refracting elements and the method described of etching the grooves is both cheap and practical. In the bulb illustrated, the concave grooves are separated one from the other by rounded ridges, 7, 7. The edges of the ridges are rounded by the action of the acid in forming the grooves. These ridges may vary in width to from 1m to 1/450: human t esantas withouti .a'fiectingithe reptical nfi'ect ot the coneavellightiscattering surfia-eesidfathe bulbir fine \idist-inet .;species .raof'. ml. invention};

, which sis .;of great mmmercia" evalue,- 1511 1 volveszthei-uselzofggroeves, smnarmw ands-am closely spaced,- that whenrvinveeda'fromaihe' ordinary distances-lot ariewz'feetathei images produced :hy zzthe riindividmel :refraeting role-i m ments iappearrto lhlendrin tone gpractieallyl uniform bau'dcofelight. EWhemthisarnangement iszappliedtto the '1 ordinary-.eommercml! tungstendamp;aboverdfierredto;the superposed or loverrlapping reflect ref 1: the Lmulti-z plic ty.ofefilament.lengthsreachthuswidens:

Qut-,-;as -.;to;.-praduce zupon ether-eye .off the .observer. 1 the 5 effect of an ;approximately llllliform (blaze 015 '1 light ,emitted :from a the :sur-l "face lot {the bulb ;over a wideiaarea whichl mayhinclude ia;largexportion ofrawurfiaeei of: thehulb onrthegside; toward the =.observer..1

' The rah veareferred "i0; PHIGtlCflIYydQSiPhblfl form (oflamp, has the i ordinary; thin .tlighti bulb, :rWhiChg'tiS particularly desirable and! commercially almost indispensable: for mi lamp (to :be isold, win .1 the opens-market 'llhe grooves ,ef the;: desired width,-;- sayv.less thanl 1/100 often ,1nch',-\ very' closely, spaced,- or, it; desired, separated b distances :not greater} thorns/10 of. the-wvi th ofa;groove -maybe; formed r' .OI1 the exterior walls @of' the :bulb; atter it as iblowniiinmrshape by carefully; etching to a -.depth preferably 1! not reater; than @1/3 the: thiclmess of, the thin-Wail of: the;

. bulb. lhe fetching heiw' Z- by chemical reaction, avoids. dangergof i producing orn developing -,inc ipient 'Jfuactures .or .-inter-nalg stresses: such might render t-he bulbtoo; fragile for commercial transportation rand;-

. ,It will. be seen that; the above 2 specific.- embodiment of my ,invention involves concurrent factors of great :adv-antage in connection with the. thinwalledrbulbs of com-f f rmerce. First; The formationof the- 'grooves by, .achemical j process, eliminates; all danger;

of incipient fracturesywhich unight result from molding. Second: EB)" making zthe; grooves narrow .and (closely spaced, .th eiri:

depth need. not exceed 1/3, the. thickness of, the wall of the ordinary commercial abulb;

. Third This a same narrowness, vshallowness and closeness. in spacing, -may Joe: utilized to.

give. the-functional advantage :of causin -.the" -.o ptical effect-of an approximately uni 0mm blaze of:{-light.,or;iginating overithe. entire or. a :large portion gofithe surfaee of. the -b1'1lb.; Theabove factors-all have a special rela-; tion to the intensity of. light produced. .by

60'jhigl1 ,efl iciency, multiple length metallicfilament 'lamps ofthe modern type, ,iIls-SO- much ;as'ithe uniform blazeof'lightwhich;

.may be thus caused to originate with-vtheapparent .uniformity from practically. all

rof.,. t h je. available surface. of the. b.ulb, is.= quite L asiiiiitense; as) is agreeable when viewed .=diirectly by the human.eye.- :The result .fromiawonsuimersview 113011112 :is a :tungsten-or similar; lam with :a xhulb hazing the-same vor even. less Wei ht than t e commercial tbulb, together wisi all other advantagesiof ypizoduixing efiiciency. I iI'u Fig-53,11 haveishown diagrammatically i the rgeneral reflect of s the.;elongated 1 concave refnacting :surtaeesor 3 lenses 6, '16 upon the :raysinflightemittedifromithem. -=l?he .porition .of the zhnlb illi1strated,.=is 1 greatly (en f largedand s the; grooves are more -=accurately :formed and spaced :than ..-.is inecessary all} zarctual -a:prac t-ice.- ;;-Each :refracting element sscattens the :rays ,=.emitted =by it, through a :wideamnaas'showmat 9,. 9 iIla E g.-3. Rays (emitted-from one :of; the grooves 6, 6- will; he I 1 projected ialongsstraight. lines,.- such, for. example, yas thehnes a, l) c,'d,,e,.-fand g,awhich I ms; shown, first converge .and meet at. a. more ortless :wellv defined .focal point, h and then 1 diverge lthroughsa Wide angle,,o, -]b, .g and gthe amount of light emitted from one reifracting element and 1 received at; any .point $such-:.-as.-.a, t e, d e, :f, orgy 'willrbezdiminlished proportionately to the wideness-of-the angle. hileeach single ,groove .6, scatters l the; light transmitted through it,.'inthe; man; mer, described, it will be apparent! that each :of the mult plicity iofladjacent parallel gg'roovesifinwil-l also emit-flight insa similar: nnanner and thatsome of: the rays from each aadiacent groove on; the-same side ofzthe bulb,-,

grooves as shown, for example, at w in Fig." -53. The grooves lO0a/t6d'z8.t19 9,99, 9 E9f, .99, "and .9 'being eachsimilar to the ilensrforming-surfaces locatedr-at 9,..9,- will- =each emit rays which converge .-.and ;.then ;are scattered through a ;wide angle, :as 'rozughly indicated at =9,- 9, but, eacl1-sueh sur- {face will emit rays which-travel towardzthe Ejector vthe'e'ye-of m observer located at 0' receives ;1 ight from large number 1 of :secionidary sources, each of which .is dimmer livered by the lamp orqfila-menttojhevarimarked, the Eli-ght being :more evenly :dis-

;tribu.ted,-and the -eflect is toypr0duce-thetap 30 pqflirance :19? a 1 .unii orm :NVide blaze 40f, light,

;point-.w alongstraight linesso thatthe 0b- 1 -current-rconsnmption economy mndf light :Will converge with the: rays from otherthan the original source, the incandescent ions :jobjects but the contrasts 5:8;1'6 Jess :plain, polishedaand paral-lel interior and ex: x ,teriorsurfaces. It-will belobvious that's'by idistributingthe apparent sources of light [around-the.exteriorof thebulb, globe orcontainer,-.the same amount of light-T-isiiemuch more grateful to the eyesthan light direct from a filament.

The present application is a division of my co-pending application 619,733 filed April 8, 1911.

I claim -1. A lamp comprising a linear source of light and a container therefor, said con- .blend to produce the optical effect of a substantially uniform wide blaze of light.

' 2. A lamp comprising a linear source of light and a container therefor ,-'said container having a multiplicity of parallel adjacent grooves, less than 1/100 of an inch in width, etched on its exterior surface i'nrelatively close arrangement, whereby the individual images produced by the separate grooves blend to produce the optical effect of a substantially uniform'iwide blaze of light.

"3. A lamp, comprising a linear source of light and an exhausted container therefor,

provided on its external surface with a multiplicity 'of narrow, approximately parallel, shallow, groove-like, linear markings, which extend in the same general direction a's-the linear source of light and are closely spaced,

whereby a multiplicity of" the individual images of the source produced by each groove-like marking produce the optical effect of a substantially'uniform wide blaze of li ht. 4

4. A lamp, comprising a linear source of light and a blown container bulb therefor, having one surface plain and the other surface provided with a multiplicity of narrow, relatively shallow etched grooves, which extend in the same general direction as the linear source of light.

5. A lamp, comprising a linear source of light, and a container bulb therefor, having one surface plain and the other surface provided with a'multiplicity'of approximately parallel, narrow, closely spaced grooves, which extend in the same general direction as the linear source of light, whereby the individual images of the linear source produced by the separate grooves, blend to produce the optical effect of a substantially uni: form, wide blaze of light.

' 6. As an article of manufacture, a high efficiency metallic filament incandescent lamp, having the filament disposed mainly in lengths extending in the general direction of the length of the lamp and protectedjby an evacuated blown bulb of commercial thinness of wall, said bulb having a plain interior surface and having etched on the exterior surface thereof, a multiplicity of nar row, shallow, concave, adjacent, practically of 1 shallow, ,grooves with intervening convex curved ridges extending in the same general direc-' curved refracting surfaces.

grooves bein less" than half. the-thickness of the wall of t e bulb, wherebythe individual I am m.v grooves, uieli .aepa; a; said images of the linear [source of light pro-1 duced by each groove blend and" reduce the-- optical effect of: a substantia y uniform wide blaze of light. 7. An incandesce ntlamp, comprising a linear source of li ht'in combination with-a interior surface and an exterior surface;

of narrow, 'approxi' mately parallel 'ad acent grooves etched thereon and extending in the same general blown glass container bulb, having a plain having a multiplicity direction as the linear source of light.

8. An incandescent lamp, comprising a linear source of light-in combination with a" blown glass container bulb for said source,

having a plain interior surface and an extenor surface etched'to form a multlplicity narrow, concave,

adj acent tion as the source of light and affording 9. An incandescent lamp, comprising a linear source of light in combination with an exhausted glass'container, having a plain .interior surface and provided on its exterior surface with a plurality of adjacent, elongated refracting grooves with substan-' Qtially smooth surfaces, extendinginthe same general direction as the linear source of light and formed and spaced not'more than; Zone-fiftieth of an inch from center to center.

10. An incandescent lamp, comprisinga linear source of light in combination with an exhausted glass container, havin a plain interior surface and an exterior sur ace'provided' with a multiplicity of alternately ar-' ranged, narrow, elongated, concave and convex refracting surfaces of a polished nature,

the concavities being not more than one fiftieth of an inch from center to center.

11. An incandescent lamp, comprising ahydrofluoric acid and extending in the same general direction as the filament. I 12. An incandescent lamp comprising a light emitting filament, in combination with a blown container bulb for the filament, having thin glass walls, a plain interior surface, and an exterior surface provided with a multiplicity of grooves, etched by means of hydrofluoric acid and extending in the same general direction as the filament, the depth'of the grooves being not greater than approximately one-third of the thicknessof thegl'ass walls. v

'13. A lamp, comprising a linear source of light and an exhausted container therefor,

provided on its external surface with a multiplicity of narrow, approximately parallel, shallow, groove-like, closely-spaced linear markings, having practically smooth surfaces and extending in the same general direction as the linear source of light, whereby the individual images of the source produced by each said groove-like marking, unite to produce the optical effect of a practically uniform Wide blaze of light.

v14. A lamp comprising a. linear source of light and a container therefor, said container being provided on its exterior surface with a multiplicity of minute grooves set relatively close together, whereby rays received from the source are separately scattered laterally by a multiplicity of refracting surfaces and blend in the field of illumination to cause the linear source to have the optical appearance of a widened band or transversely continuous surface of light, the width of which is practically independent of the width of the source but is dependent upon the number of efiectively contributing grooves.

15. An electric lamp comprising a filament and a glass container, at surface of the container being formed with a multiplicity of elongated refracting surfaces or lenses of a width less than the thickness of the wall of the container and all extending in the same general direction with each other and with the major portion of said filament.

16. In an incandescent electric lamp, a linear source of light, in combination with an evacuated inclosing bulb having at least a portion of its wall formed with a multiplicity of refractors comprising long narrow practically transparent, refracting surfaces,

said refractors being formed so that the light received by each is refracted and emitted from the outer surface of each in a multiplicity of directions diverging later-- ally with respect to the linear source, so that diminished divergent rays from a multiplicity'of said linear refractors will converge toward a multiplicity of points in the same field of illumination, the number of refractors emitting light toward the same given points in the field being in the aggregate approximately proportional to the light scattering power of the respective refractors, and the narrowness and spacing of said refractors being such as to constitute said bulb wall a diffusing medium emitting light from a wide zone distributed laterally with. re spect to the general direction of the linear source.

17 An incandescent filament electric lamp having a blown bulb of commercial thinness, having a smooth interior surface and having formed on its exterior surface a multiplicity of minute closely-spaced depressions and elevations having substantially smooth surfaces, the distances between the tops of adjacent elevations being so proportioned to the permissible depth of the depressions as to produce the degree of steep-sidedness necessary for effective light deflection.

Signed at New York city in the county of New York, and State of New York, this 18th day of July A. D. 1911} PETER COOPER HEWITT.

Witnesses L. A. COLEMAN, R. A. HEWITT. 

